Pentax K-X Operating Manual page 94

You can display 4, 9, 16 or 36 images on the monitor at the same time.
The default setting is nine image-display.
1 Turn the e-dial to the left (toward
5€) in Playback mode.
The multi-image display screen
appears.
Up to nine thumbnail images will be
displayed at once.
Frame
Scroll bar